1. Field of the Invention
Embodiments of the present invention generally relate to the fabrication of integrated circuits. More particularly, embodiments of the present invention relate to a method for depositing a dielectric layer on a barrier layer.
2. Description of the Related Art
Semiconductor device geometries have dramatically decreased in size since such devices were first introduced several decades ago. Since then, integrated circuits have generally followed the two year/half-size rule (often called Moore's Law), which means that the number of devices that will fit on a chip doubles every two years. Today's fabrication plants are routinely producing devices having 0.13 μm and even 0.1 μm feature sizes, and tomorrow's plants soon will be producing devices having even smaller geometries.
In order to further reduce the size of devices on integrated circuits, it has become necessary to use conductive materials having low resistivity and to use insulators having low dielectric constants (k<4) to reduce the capacitive coupling between adjacent metal lines. Recent developments in low dielectric constant films have focused on incorporating silicon (Si), carbon (C), and oxygen (O) atoms into the deposited films to provide organosilicate films, such as silicon oxycarbide films.
The development of silicon oxycarbide films having both a low dielectric constant and desirable chemical and mechanical properties has been challenging. For example, it has been observed that silicon oxycarbide films having a desirably low dielectric constant less than 3.0 or less than 2.5 often do not adhere well to an underlying barrier layer, such as a silicon and carbon-containing barrier layer, during subsequent substrate processing. Some substrate processing techniques apply forces to the substrate that can increase layering defects, such as layer delamination. For example, excess copper containing materials may be removed by mechanical abrasion between a substrate and a polishing pad in a chemical mechanical polishing process, and the force between the substrate and the polishing pad may induce stresses in the deposited silicon oxycarbide films that result in delamination of the silicon oxycarbide films from adjacent layers. In another example, annealing of deposited materials may induce high thermal stresses that can also lead to delamination of silicon oxycarbide films.
Thus, there remains a need for a method of improving the adhesion of low dielectric constant silicon oxycarbide films to adjacent layers.